Stimulation (1 ma current 1 msec pulses) of the distal end of the severed sympathetic chain produced vasoconstriction in the ipsilateral horn of both pregnant and non-pregnant ewes when the uterus was perfused at constant flow with blood drawn from the ewes' carotid artery. The constriction was proportional to the frequency of stimulation in the pregnant animals. In the non-pregnant ewes, the frequency-response curve was curvilinear with the rate of change in responsiveness steepest at low frequencies (less than 10 hz) and less steep at high frequencies (15-25 hz). In the non-pregnant ewes, the response of the contralateral horn was qualitatively similar, but the curve was less steep and lay below and to the right of the curve from ipsilateral horn. In the pregnant ewes, the response of the contralateral horn was less than that of the ipsilateral horn and was independent of frequency. Dibenzylene (2 mg) administered to the ipsilateral artery abolished the responsiveness of both horns to sympathetic stimulation although responsiveness of the contralateral horn to injected norepinephrine remained intact. The data suggests that the responsiveness of the contralateral horn is due to a cord-level reflex and not to distribution of sympathetic fibers of the ipsilateral chain to blood vessels of the contralateral horn. Oxygen uptake of the perfused mid-term uterus is constant (6-7 ml/kg/min) at blood flows above 25 ml/100 gms tissue/min. Similar data for near-term ewes is not yet available. At perfusion flows below 25 ml/100 gms of tissue/min, oxygen uptake is a linear function of blood flow. For a given perfusion flow, oxygen uptake of the near-term uterus appears to be greater than at mid-term.